fix(DASH): Notify time range with the fitted timeline (#7911)

lib/dash/segment_template.js

@@ -158,7 +158,9 @@ shaka.dash.SegmentTemplate = class {
       if (info.timeline &&
           context.adaptationSet.contentType !== 'image' &&
           context.adaptationSet.contentType !== 'text') {
-        const timeline = info.timeline;
+        const tsi = /** @type {!TimelineSegmentIndex} */(segmentIndex);
+        // getTimeline is the info.timeline but fitted to the period.
+        const timeline = tsi.getTimeline();
         context.presentationTimeline.notifyTimeRange(
             timeline,
             periodStart);
@@ -934,6 +936,19 @@ shaka.dash.TimelineSegmentIndex = class extends shaka.media.SegmentIndex {
     // find/get() methods whenever possible.
   }
 
+  /**
+   * Get the current timeline
+   * @return {!Array<shaka.media.PresentationTimeline.TimeRange>}
+   */
+  getTimeline() {
+    if (!this.templateInfo_) {
+      return [];
+    }
+    const timeline = this.templateInfo_.timeline;
+    goog.asserts.assert(timeline, 'Timeline should be non-null!');
+    return timeline;
+  }
+
   /**
    * @override
    */